<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>点击发送</button>
    <button>点击取消</button>
    <script>
        const btns = document.querySelectorAll("button");
        let xhr = null;
        btns[0].addEventListener("click",function(){
           xhr = new XMLHttpRequest();
           xhr.open("GET",'http://127.0.0.1:8000/delay');
           xhr.send();
        })
        btns[1].addEventListener("click",function(){
            //取消请求
            xhr.abort();
        })
    </script>
</body>
</html>